We consider the problem of determining the voltage in coil rings, which arise as an axisymmetric approximation of a single connected induction coil during modeling of induction heating. Assuming axisymmetric electromagnetic fields with sinusoidal time dependence, we compute the voltages from the condition that the total current must be equal in each ring. Depending on whether total current, total ...
View full abstract»

The paper reviews several expressions for high-frequency winding resistance of inductors proposed by several authors and compares the theoretical predictions calculated from these expressions with experimental results. It identifies the expressions that yield the most accurate prediction of the winding high-frequency resistance. The comparison shows that the method proposed by Dowell (1966) accura...
View full abstract»

We evaluate a testing specification proposed by the National Storage Industry Consortium's (NSIC) Extremely High Density Recording (EHDR) group for evaluating head and media compatibility for servo performance in magnetic disk drives. These tests use average amplitude and average noise profile measurements across isolated tracks to predict the shape, linearity, noise, and long-term stability of po...
View full abstract»

We measured tensor hysteresis loops for a 25.4 mm steel cube with compressive stress applied orthogonal to the field, and studied the repeatability of compressive stress effects in terms of the maximum magnetization and differential susceptibility amplitudes. The nonrepeatability of results and anomalous low stress behavior can be attributed to stress hysteresis, specifically to residual stress
View full abstract»

We present a recently developed multigrid calculation scheme for coupled magnetomechanical systems. The scheme allows the efficient calculation of three-dimensional (3-D) dynamic rigid motions as well as deformations of nonmagnetic and ferromagnetic materials in a magnetic field. Thereby, the 3-D mechanical problem is discretized with nodal elements and the 3-D magnetic problem with edge elements....
View full abstract»

We investigated the static and time-dependent magnetic properties of thin CoSm films (6-14 nm) on CrV underlayers. We measured remanent coercivities of up to 4.5 kOe and viscosity coefficients as low as 8%/decade for 14-nn films with remanent moment thickness product of 0.49 memu/cm2. We compared magnetic hardness, interactions, viscosity, and anisotropy with similar films grown on Cr u...
View full abstract»

This paper presents analytical expressions for coil impedance due to a spherical workpiece consisting of concentric spherical shells. The expressions are used to simulate the nondestructive inspection of a sphere having arbitrary radial conductivity and magnetic permeability profiles by a circular coil of rectangular cross section. The simulation replaces continuous profiles with piecewise constan...
View full abstract»

The paper proposes an efficient solution strategy for nonlinear three-dimensional (3-D) magnetic field problems. The spatial discretization of Maxwell's equations uses Lagrange finite-element functions. The paper shows that this discretization is appropriate for the problem class. The nonlinear equation is linearized by the standard fixed-point scheme. The arising sequence of symmetric positive de...
View full abstract»

This paper presents a novel technique for integrating yttrium iron garnets, namely Ce:YIG, onto semiconductor platforms using metal-organic chemical vapor deposition (MOCVD). Large amounts of cerium (Ce) could be incorporated into the garnet structure because of the nonequilibrium nature of the technique. The method can alloy up to 54% Ce, thereby increasing the refractive index and enhancing the ...
View full abstract»

We evaluate the use of linear and nonlinear inverse algorithms (maximum entropy method, low resolution electromagnetic tomography, L 1 and L2 norm methods) in the analysis of magnetic flux leakage (MFL) measurements commonly used for the detection of flaws and irregularities in gas and oil pipelines. We employed MFL data from a pipe with well-defined artificial surface breaki...
View full abstract»

This paper presents a magnetic efficiency model for comparing efficiencies of various magnets for magnetic resonance imaging. It demonstrates that monohedral magnets, magnets with sources on one side, can generate remote saddle points in the field profile relatively efficiently. These magnets may be modeled by a minimum of two magnetic dipoles. The paper examines the field profile and magnetic dip...
View full abstract»

In this paper, a novel multiobjective optimization method based on a genetic-fuzzy algorithm (GFA) is proposed. The new GFA method is used for optimal design of a switched reluctance motor (SRM) with two objective functions: high efficiency and low torque ripple. The results of the optimal design for an 8/6, four-phase, 4 kW, 250 V, 1500 r.p.m. SRM show improvement in both efficiency and torque ri...
View full abstract»

The magnetoresistive (MR) magnetic head is a poor positioning transducer for a disk file's servo control system because its positioning response is nonlinear with radial displacement. This paper shows how the MR head's poor positioning properties are alleviated by a self-adjusting adaptive algorithm that allows a disk file to linearize its own servo position error signal (PES). The adaptive linear...
View full abstract»

We report an investigation and theoretical assessment of the DC magnetic properties of high-permeability grain-oriented (GO) Fe-Si laminations under variously directed applied fields. We verified that normal magnetization curves, hysteresis loops, and energy losses depend on the field direction according to the sample geometry. This is explainable in terms of specific 180° and 90° domain w...
View full abstract»

In this paper, we introduce a contact-free moving-magnet type of positioner that uses magnetic levitation to eliminate friction, the major limiting factor to high resolution on the micromanufacturing level. The promising magnetic structure consists of permanent magnets mounted on the stage and air-core solenoids, with little uncertainty, fixed on the stator. Since magnetically levitated systems ar...
View full abstract»

This paper presents a new type of conformal mapping function of two unequal segments onto equal ones. It develops analytic expressions for calculation of the magnetic field strength and electromagnetic ponderomotive force. Finally, it compares theoretical values with experimental data
View full abstract»

This paper deals with the characterization of the magnetic permeability of soft magnetic materials under a rotating magnetic field. The paper reviews the principle of the rotating-flux-density device used for measurement of flux density, then describes the mathematical method used to calculate permeability from the measurements. The method combines direct and inverse solutions and is based on a fu...
View full abstract»

A high-performance magnet generating a homogeneous field contributes significantly to the quality of magnetic resonance imaging (MRI), and permanent-magnet assemblies, which can be specially configured for the particular whole body, pediatric, or orthopedic use, unlike superconducting and resistive magnets, help to ensure homogeneity. The paper surveys the suitability of tunnel-like, ordinary, and...
View full abstract»